In a general wireless communication system, since signals are transmitted and received through a direct link between a base station (BS) and a user equipment (UE), a radio communication link having high reliability may be easily configured between the BS and the UE. However, the wireless communication system has low flexibility in a radio network configuration because the location of the BS may be fixed. In addition, in wireless environments in which traffic distribution or variation in the amount of call demands is wide, it is difficult to provide an efficient communication service. To overcome such shortcoming, a data transfer scheme of a multi-hop relay form using fixed relays, mobile relays, or general UEs may be applied to a general wireless communication system.
A wireless communication system using a multi-hop relay scheme may reconfigure a network by rapidly coping with a communication environment variation and may efficiently manage all wireless networks. For example, the wireless communication system using the multi-hop relay scheme may extend cell service area and increase system capacity. That is, when a channel state between the BS and the UE is poor, a relay may be installed between the BS and the UE to configure a multi-hop relay path through the relay, thereby providing the UE with a radio channel having an excellent channel state.
In addition, a higher data channel speed may be provided by using the multi-hop relay scheme in a cell edge area having a poor channel state from the BS and a cell service area can be extended.
Thus, the relay is widely being used as a technique introduced to eliminate an electromagnetic waveform shadow zone. The relay was restricted to a repeater function in the past to simply amplify and transmit signals, whereas the relay has recently evolved into a more intelligent type.
Furthermore, the relay technique is a technology required to reduce BS installation costs and backhaul network maintenance costs in a next-generation mobile communication system and simultaneously to improve service coverage area and data throughput. As the relay technique has gradually developed, a new wireless communication system needs to support relays used in a conventional wireless communication system.